Tesla's Powerwall costs $6,200 and can store 14 kilowatt-hours of energy. For reference, the average electricity consumption for a residential customer in 2015 was 901 kWh a month.

One battery can provide 5 kW of continuous power and improve to 7 kW at its peak.

Tesla's first-generation Powerwall.
YouTube/VideoMisery

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"You can actually, if you want, go completely off-grid," Musk said during the Powerwall's unveiling in 2015. "You can take your solar panels, charge the battery packs, and that's all you use."

Reuters/Patrick Fallon

It's important to note that the Powerwall still relies on the electrical grid for periods of high demand. But it can operate independently by just running on solar power. That means Puerto Ricans could use the Powerwall to fulfill their basic electric needs until grid repairs are made.

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The Powerwall can only be set up by a certified installer. The installations cost between $800 and $2,000.

Tesla

Some third-party installers have been charging excessive premiums in Puerto Rico. Musk said the company will stop shipping units to installers who are ramping up costs — a Powerwall shouldn't cost more than $8,200 to purchase and install.

Tesla is also working on sending more experienced installers to Puerto Rico to help train locals.